why is my mesh's UV's not displaying right when importing my Mesh

Hey guys so here’s my problem; I’m making a scaffold model in blender and when I very first imported it into UE4 it imported just fine and I added my materials to it and made it look just the way I wanted to but when I built the lighting it had some nearly zero bi normals and overlapping UV’s so my model ended up looing terrible so I went back in blender I noticed that all my UV’s had the same name. (scaffold model is made up of several different models with different UV’s joined together) since they had the same name they got stacked on top of each other which mad them overlap. so I rebuilt the scaffold again but I named each UV with a model specific name which stacked them in layers now when I join the models together. but the model is only displaying one of the UV’s correctly in the whole model. you’ll see in the pictures that the shortest leg has chipped paint marks in it which is what its supposed to look like and then the rest of the scaffold if I add the material to it just shows up a solid color no matter what I do im assuming im doing something wrong in blender but i figured i would ask here too incase anyone ran into the same problem. thanks everyone!!

just off the top of my head I had a problem with lighting when I upgraded engine version, I can’t remember exactly think I had to put the light intensity of one of my lights right down from 10000 to a hundred or something or even 2, you could experiment with extreme high/low intensity, my models looked very badly lit until I figured it was extreme intensities causing a strange effect, I was telling myself there was no way that could be the problem at first.

Ok I’ll try that; thank you!!!